The present invention relates to an improved winterfront to restrict the flow of cold ram air through the grill of a moving truck having a grill without a center bar spanning the width of the grill. More specifically, this invention relates to a winterfront with an air opening that is symmetrical about the axis of rotation of the engine fan of such trucks.
Winterfronts have long been used on large trucks during periods of cold weather in order to restrict the flow of cold ram air through the grills of the trucks. Absent the use of such a winterfront, ram air impacting the grill of a moving truck flows through the entire front face of the grill, past the radiator, and then through and around the engine fan toward the engine and driver's compartment of the truck. With such a winterfront, ram air impacting the front of the moving truck is allowed to contact and flow through only a portion of the grill. Hence, the winterfront restricts the quantity of ram air flowing through the grill, past the radiator, and past the engine fan to the engine or driver's compartment.
The winterfronts in the prior art are comprised of a ram-air-blocking fabric that covers a portion of the grill of the truck and fasteners that serve to removably attached the fabric to the truck grill. The fabric is usually comprised of one or more sections of sandwiched, weather resistant polymeric sheets, and the fasteners are often "common sense" or "lift-the-dot" type with the male or stud parts of the fasteners being attached to the grill or other front section on the truck and the female parts being attached to the periphery of fabric.
For trucks with grills that do not have a center bar spanning the width of the grill, the winterfronts in the prior art have, in their ram-air-blocking portions, air openings that are off-center or asymmetrical about the center of the radiator--the position on the radiator which lies in a line that is approximately colinear with the axis of rotation of the engine fan. Only a portion of the ram air impacting the winterfront is allowed through these asymmetrical openings. The openings are either (a) "V" shaped openings abutting the upper half of the radiator, (b) inverted "V" shaped openings abutting the lower half of the radiator, or (c) rectangular shaped openings abutting either the uppermost portion or lowermost portion of the grill. Examples of some of these types of winterfronts are Product Nos. WF-1369 and WF-1206 manufactured by Belmor Manufacturing Co., Chicago, Ill.
These winterfronts in the prior art have not provided for a symmetrical distribution of ram air through the radiator about the axis of rotation of the engine fan. As a result, the winterfronts in the prior art cause an uneven or asymmetrical distribution of ram-air foces on the rotating fan blades of the truck's engine fan. Even though years ago it became widely known in the industry that this uneven distribution of ram air forces on the fan blades was possibly causing unnecessary damage to fan blades, fan axles, and fan bearings, no workable solution to the problem has been found prior to the present invention disclosed herein.
The problem of asymmetrical and off-center distribution of ram air about the axis of rotation of the engine fan became even more acute in the mid-seventies because of the fuel shortage. That is, the problem became even more acute because of its effect on certain types of "uncoupling" engine fans, leading to decreased engine efficiency and increased fuel consumption.
As far back as the early seventies, truck manufacturers began to attempt to increase the efficiency of their engines by installing engine fans that ucouple, either partially or totally, when a temperature sensor senses that the engine has been cooled to the desired level. The rotation of such fans thus slows down or ceases until the temperature sensor senses that the temperature of the engine has risen above a certain level. Once the temperature of the engine is sensed to have risen above that certain level, the fan is again engaged to cool the engine down. Because such an engine fan operates only as necessary for cooling the engine, they are much more efficient than permanently coupled fans and result in increased fuel efficiency of the truck. As the fuel shortage of the mid-seventies appeared, such uncoupling fans became recognized as an extremely useful and economical method of increasing the fuel efficiency of truck engines.
Many of the temperature sensors referred to above are of the "viscous clutch" type, which sense the temperature of air near the area surrounding the fan axle of the engine fan. When winterfronts having asymmetrical or off-center openings are used on trucks having such "viscous clutch" temperature fans, the flow of air past the centrally located temperature sensor is severely restricted. The lack of direct ram air flow past the sensor causes the senor to sense a higher temperature so the sensor needlessly engages, or increases the rotational velocity of, the fan. The result is an overall decrease in engine efficiency and corresponding increase in fuel consumption by the truck.
In addition, for all types of "uncoupling" engine fans, the impact of the ram air against the fan blades of the engine fan causes a "free wheeling" effect. That is, the engine fan is driven by the air impacting the fan blades without any driving force or effort from the engine of the truck. However, the winterfronts in the prior art having asymmetrical or off-center openings do not fully utilize this free wheeling effect since ram air unevenly impacts the fan blades. This lack of full utilization of the free wheeling effect causes an additional overall decrease in efficiency of the engine on the truck.
Lastly, those winterfronts in the prior art that have asymmetrical openings in the upper portion of the winterfront often cause heating problems in cab-over-engine type trucks. Such winterfronts direct cold ram air over the top of the engine against the floorboard or instrument panel of the passenger compartment.
It is therefore an object of the present invention to provide for use on trucks that do not have a center bar spanning the width of their grills a winterfront that provides a more even distribution of ram air forces on the fan blades, fan axle, and fan bearings of a truck.
It is a further object of the present invention to provide for trucks without such center bars a winterfront that directs ram air through the grill toward and around the fan axle of the engine fan. In this way, a "viscous clutch" type engine fan will more properly engage or disengage, thereby increasing the engine efficiency and decreasing fuel consumption of the truck.
It is also an object to provide a more complete, symmetrical, and centered distribution of ram air on the fan blades of trucks so that an "uncoupling" type engine fan can fully utilize the free wheeling effect to increase engine efficiency.
It is yet another object of the present invention to provide for cab-over-engine type trucks without center bars on the grill, a winterfront that directs the cold ram air against the engine fan and engine rather than against the floorboard or instrument panel of the cab.
It is also an object of this invention to provide trucks without such center bars a winterfront with a center opening that is adjustable in size, and no matter how adjusted, always provides a more even distribution of ram air forces on the fan blades, fan axle, and fan bearings of a truck.
Other objects and advantages of the present invention will become apparent as the specification proceeds.